06/27/2008 at 04:00 PM EDT
If it were up to her 3-year-old son Ben, Alison Sweeney wouldn't be giving birth to a new baby.
"When we showed him a picture of the ultrasound and asked him, 'Would you like a little brother or sister?' he said 'Can it be a helicopter?' " Sweeney tells PEOPLE. "So ... we're working on it."
Helicopters notwithstanding, whether baby No. 2 is a boy or a girl, the expectant Biggest Loser host is thrilled about being a mom for the second time.
"The whole experience of having a little girl, I'd love that," Sweeney, 31, said on the eve of the New York City casting call for Biggest Loser 7, happening in Rockefeller Center on Saturday. "Whenever I'm out shopping for Ben, my heart cries out for all those adorable little girls clothes. But having a little boy would be great, too. I love having a boy, and I would definitely not mind having another."
Eleven weeks along with her second child with husband Dave Sanov, Sweeney is eager to find out which gender she'll be getting. "I'll go in for a high-tech ultrasound at the third month and will find out,” she says.
As for right now, Sweeney is focused on staying fit with four workouts a week, and eating healthily for two – despite battling "queasy" afternoons. "I love chicken but I can't look at it right now. Luckily my favorite Greek yogurt, Fage yogurt, hasn't turned me off yet. I put sliced almonds and cinnamon and strawberries in my yogurt with a little Splenda, and it's so good."
Casting calls for Biggest Loser 7 will be held in 11 cities throughout the summer.